1. Technical Background
The present invention relates to a catheter, and more particularly to a catheter with a centering tip.
2. Discussion
Percutaneous transluminal coronary angioplasty (PTCA) and stenting are therapeutic medical procedures used to increase blood flow through the coronary arteries and can often be used as alternatives to coronary bypass surgery. In PTCA procedures, the angioplasty balloon is inflated within the narrowed or stenosed vessel, at the desired location for treatment, such as an atheroma or plaque deposit, in order to obtain an enlarged opening or lumen. In stenting, an endoluminal prosthesis of any appropriate type is implanted in the vessel to maintain patency following the procedure. In order to initiate these procedures, one must first introduce a guidewire into the lumen of the vessel to serve as a conduit for other interventional devices, such as angioplasty balloons and stent delivery systems. This guidewire must be advanced into a position past the location of the stenosis. Additional interventional devices, such as angioplasty balloon catheters and stent delivery systems, are then advanced over the guidewire and positioned at the site of the stenosis, to initiate therapeutic treatment of the lesion.
A common treatment method for using such an angioplasty balloon catheter or stent delivery system is to advance the catheter into the body of a patient over the guidewire, by directing the catheter distal end percutaneously through an incision and along a body passage until the device is located within the desired site. One difficulty commonly encountered with the procedure is that irregularities of the lumenal surface and narrowing of the passageway may result in delivery difficulty, because the distal end of the balloon catheter or the stent delivery system may “catch” on the wall surface. This may cause a challenge in reaching the targeted position in the vessel, and therefore may inhibit successful treatment of the lesion. Another difficulty that is encountered with this procedure is that once the target lesion is reached, stent deployment may not be perfectly uniform if the stent delivery system is not centered within the vessel. This lack of centering may result in the stent cells around the circumference of the stent not opening up completely, resulting in non-uniform deployment. The end result may be reduced strength and incomplete stent scaffolding of the vessel, and a less than optimal clinical result.
The general concept of a centering catheter for treating a body vessel with a radioactive source is well known in the art. See, for example, U.S. Pat. Nos. 6,224,535 and 6,267,775.
However, the art has yet to disclose or suggest any devices for centering a non-radiation source catheter during its entire journey through the vasculature and to the treatment site, to facilitate access to tortuous anatomy, and then to promote uniform deployed stent expansion at the treatment site.
The present invention provides for a centering catheter which operates to remain centered during its entire journey through the vasculature and toward the treatment site, as well as at the treatment site, and which overcomes many of the disadvantages associated with the use and operation of prior art devices.
An objective of the present invention is to facilitate access to tortuous anatomy, so that a lesion location may be more easily reached and the vessel may be treated. Another objective of the present invention is to facilitate uniform deployed stent expansion by stabilizing the stent delivery system catheter and centering it in the vessel during stent deployment.
The centering catheter of the present invention comprises an elongated catheter body having a proximal end and a distal end, and at least one centering device attached near the distal end of the catheter. The centering device comprises a proximal end and a distal end and at least two struts extending therebetween. The centering device has a smaller diameter for insertion into a lumen and a larger diameter for expanding to substantially equal the diameter of the lumen and to center the catheter within the lumen. The centering device also has a plurality of intermediate diameters, between the smaller diameter and the larger diameter. These intermediate diameters may be utilized as the centering device adjusts to diameter variations in the lumen of the vessel during the catheter journey through the vasculature and toward the treatment site. Once the site is accessed, the centering device may also facilitate uniform stent delivery for either balloon expandable or self-expanding stents, by centering the distal end of the catheter during the deployment of the stent. Uniform stent expansion may contribute to a successful clinical outcome by insuring that optimal scaffolding of the vessel has occurred and optimal radial strength has been achieved to resist elastic recoil of the vessel following an interventional procedure. The catheter may then be withdrawn from the lumen of the vessel.
In accordance with one aspect, the present invention is directed to a catheter having at least one centering device attached near the distal end of the catheter. Each centering device comprises a proximal end and a distal end and at least two struts extending therebetween. Each centering device preferably has a variable diameter that centers the distal end of the catheter, steering the catheter away from the vessel wall during its insertion through the vasculature to the treatment site.
In accordance with another aspect, the present invention is directed to a stent delivery system comprising at least one centering device attached near the distal end of the stent delivery system. Each centering device comprises a proximal end and a distal end and at least two struts extending therebetween. Each centering device preferably has a variable diameter that centers the distal end of the catheter during the process of stent deployment.
An advantage of the present invention is that the sometimes-tortuous anatomy of the vasculature may be more easily traversed while avoiding lumen damage, and access to the lesion location may be facilitated by the availability of a centering device that centers the catheter throughout its introduction into the vessel. Another advantage of the present invention is that the centering device may stabilize the distal end of the catheter during stent expansion, and may therefore allow the operator to achieve a more uniform stent expansion with resultant clinical benefits to the patient.